The Ecology of Star Clusters and Intermediate‐Mass Black Holes in the Galactic Bulge

Zwart, Simon F. Portegies; Baumgardt, Holger; McMillan, Stephen L. W.; Makino, Junichiro; Hut, Piet; Ebisuzaki, T.

doi:10.1086/500361

Cited by 134 publications

(92 citation statements)

References 78 publications

(105 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…It is not yet clear how the young (few Myr old) population in the central parsec has been formed, since the tidal field of Sgr A* prevents "normal" star formation via cloud collapse (e.g. Nayakshin 2006b; Portegies Zwart et al 2006). However, the possibility of YSO presence in the central parsec was discussed by Eckart et al (2004) and Mužić et al (2008).…”

Section: Nature Of the Source At The Position Of X7mentioning

confidence: 99%

Comet-shaped sources at the Galactic center

Mužić¹,

Eckart

Schödel

et al. 2010

A&A

View full text Add to dashboard Cite

Context. In 2007 we reported two comet-shaped sources in the vicinity of Sgr A* (0.8 and 3.4 projected distance), named X7 and X3. The symmetry axes of the two sources are aligned to within 5 • in the plane of the sky, and the tips of their bow shocks point towards Sgr A*. Our measurements show that the proper motion vectors of both features are pointing in directions more than 45 • away from the line that connects them with Sgr A*. This misalignment of the bow-shock symmetry axes and their proper motion vectors, combined with the high proper motion velocities of several 100 km s −1 , suggest that the bow shocks must be produced by an interaction with some external fast wind, possibly coming from Sgr A*, or from stars in its vicinity. Aims. We have developed a bow-shock model to fit the observed morphology and constrain the source of the external wind. Methods. The result of our modeling gives the best solution for bow-shock standoff distances for the two features, which allows us to estimate the velocity of the external wind, making certain that all likely stellar types of the bow-shock stars are considered. Results. We show that neither of the two bow shocks (one of which is clearly associated with a stellar source) can be produced by the influence of a stellar wind of a single mass-losing star in the central parsec. Instead, an outflow carrying a momentum comparable to the one contributed by the ensemble of the massive young stars can drive shock velocities capable of producing the observed comet-shaped features. We argue that a collimated outflow arising perpendicular to the plane of the clockwise rotating stars (CWS) can easily account for the two features and the mini-cavity. However, the collective wind from the CWS has a scale of >10 . The presence of a strong, mass-loaded outbound wind at projected distances from Sgr A* of <1 in fact agrees with models that predict a highly inefficient accretion onto the central black hole owing to a strongly radius dependent accretion flow.

show abstract

Section: Nature Of the Source At The Position Of X7mentioning

confidence: 99%

Comet-shaped sources at the Galactic center

Mužić¹,

Eckart

Schödel

et al. 2010

A&A

View full text Add to dashboard Cite

show abstract

“…For example, many such massive young globular clusters are observed in the pair of Antennae Galaxies. In massive young globular clusters a variety of dynamical interactions take place between massive stars, massive binaries and stellar remnants (black holes, neutron stars) ranging from direct collisions to companion exchanges in binary systems, and to the formation of so-called Intermediate Mass Black Holes (IMBHs) with masses of order 100 to 1000 solar masses (Zwart et al 2002(Zwart et al , 2004(Zwart et al , 2006. These can be unique events, which do not occur in any other stellar environment.…”

Section: Host Galaxy Characteristics: Further Evidence For An Associamentioning

confidence: 99%

Long gamma-ray burst progenitors: boundary conditions and binary models

Heuvel

Yoon

2007

Astrophys Space Sci

View full text Add to dashboard Cite

The observed association of Long Gamma-Ray Bursts (LGRBs) with peculiar Type Ic supernovae gives support to Woosley's collapsar/hypernova model, in which the GRB is produced by the collapse of the rapidly rotating core of a massive star to a black hole. The association of LGRBs with small star-forming galaxies suggests low-metallicity to be a condition for a massive star to evolve to the collapsar stage. Both completely-mixed single star models and binary star models are possible. In binary models the progenitor of the GRB is a massive helium star with a close companion. We find that tidal synchronization during core-helium burning is reached on a short timescale (less than a few millennia). However, the strong core-envelope coupling in the subsequent evolutionary stages is likely to rule out helium stars with main-sequence companions as progenitors of hypernovae/GRBs. On the other hand, helium stars in close binaries with a neutron-star or black-hole companion can, despite the strong core-envelope coupling in the post-helium burning phase, retain sufficient core angular momentum to produce a hypernova/GRB.

show abstract

“…It is unclear how these young stars have been formed in the strong tidal Appendix A is available in electronic form at http://www.aanda.org field of the super-massive black hole (SMBH) at the position of SgrA*. There are two prominent scenarios: one includes star formation in-situ (in an accretion disk; Levin & Beloborodov 2003;Nayakshin et al 2006), the other requires the in-spiral of a massive stellar cluster that formed at a safe distance of 5−30 pc from the Galactic center (Gerhard et al 2001;McMillan & Portegies Zwart 2003;Kim et al 2004;Portegies Zwart et al 2006). Currently the in-situ scenario appears to be favored by a number of authors (Nayakshin & Sunyaev 2005;Nayakshin et al 2006;Paumard et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Near-infrared proper motions and spectroscopy of infrared excess sources at the Galactic center

Eckart¹,

Mužić²,

Yazici³

et al. 2013

A&A

152

View full text Add to dashboard Cite

Context. There are a number of faint compact infrared excess sources in the central stellar cluster of the Milky Way. Their nature and origin is unclear. In addition to several isolated objects of this kind there is a small but dense cluster of comoving sources (IRS13N) located ∼3 west of SgrA* just 0.5 north of the bright IRS13E cluster of Wolf-Rayet and O-type stars. Based on the analysis of their color and brightness, there are two main possibilities: (1) they may be dust-embedded stars older than a few Myr; or (2) very young, dusty stars with ages younger than 1 Myr. Aims. We present a first K s -band identification and proper motions of the IRS13N members, the high-velocity dusty S-cluster object (DSO, also referred to as G2), and other infrared excess sources in the central field. Goal is to constrain the nature of these source. Methods. The L -(3.8 μm) K s -(2.2 μm) and H-band (1.65 μm) observations were carried out using the NACO adaptive optics system at the ESO VLT. Proper motions were obtained by linear fitting of the stellar positions extracted by StarFinder as a function of time, weighted by positional uncertainties, and by Gaussian fitting from high-pass filtered and deconvolved images. We also present results of near-infrared (NIR) H-and K s -band ESO-SINFONI integral field spectroscopy of the Galactic center cluster ISR13N. Results. We show that within the uncertainties, the positions and proper motions of the IRS13N sources in K s -and L -band are identical. The HK−sL colors then indicate that the bright L -band IRS13N sources are indeed dust-enshrouded stars rather than core-less dust clouds. The proper motions also show that the IRS13N sources are not strongly gravitationally bound to each other. Combined with their NIR colors, this implies that they have been formed recently. For the DSO we obtain proper motions and a K s -L -color. Conclusions. Most of the compact L -band excess emission sources have a compact H-or K s -band counterpart and therefore are likely stars with dust shells or disks. Our new results and orbital analysis from our previous work favor the hypothesis that the infrared excess IRS13N members and other dusty sources close to SgrA* are young dusty stars and that star formation at the Galactic center (GC) is a continuously ongoing process. For the DSO the color information indicates that it may be a dust cloud or a dust-embedded star.

show abstract

The Ecology of Star Clusters and Intermediate‐Mass Black Holes in the Galactic Bulge

Cited by 134 publications

References 78 publications

Comet-shaped sources at the Galactic center

Comet-shaped sources at the Galactic center

Long gamma-ray burst progenitors: boundary conditions and binary models

Near-infrared proper motions and spectroscopy of infrared excess sources at the Galactic center

Contact Info

Product

Resources

About